CODEWITHSUNDEEP
assemblyinputkeyboarddos
Arnas
Arnas

Reputation: 327

How to access keyboard directly trough I/O ports (in DOS)?

I'm writing a program for DOS and I want to get keyboard input. The thing is that I don't want to get that input using BIOS or DOS. What's the proper way to get keyboard input without using DOS or BIOS? I mean what's the way to get keyboard input in the lowest level of programming using I/O ports. Thanks!

Upvotes: 0

Views: 2713

Answers (1)

Jesus Ramos
Jesus Ramos

Reputation: 23268

You need to do an inb instruction on port 0x60 to read the scancode from the keyboard.


static inline uint8_t inportb(uint16_t port)
{
    uint8_t ret;
    asm volatile ("inb %1, %0" : "=a" (ret) : "dN" (port));
    return ret;
}
scancode = inportb(0x60);

If you want to know when there's new input you need to setup an interrupt handler to listen for PS/2 interrupts or use USB polling depending on your keyboard.

Upvotes: 1

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